Correct Answer: C

Rationale: When caring for a child with probable appendicitis, sudden relief from pain is a critical sign that could indicate perforation of the appendix. Perforation results in the release of pressure and inflammation, leading to a temporary relief of pain. Anorexia (loss of appetite) and decreased abdominal distention are symptoms commonly associated with appendicitis itself, not perforation. Bradycardia (slow heart rate) is not typically a direct manifestation of appendicitis or its complications.

Correct Answer: B

Rationale: Rectal bleeding is more commonly associated with ulcerative colitis (UC) than with Crohn disease (CD). While both conditions can cause abdominal pain and growth issues, bleeding is a hallmark of UC due to its superficial mucosal inflammation. Perianal lesions are more characteristic of CD, and growth retardation is typically not a direct clinical manifestation of either CD or UC.

Correct Answer: C

Rationale: The correct answer is C because Crohn's disease commonly presents with pain, severe weight loss, and moderate to severe diarrhea in affected individuals. Therefore, all the manifestations listed are typically observed in patients with Crohn's disease. Choice A alone is not sufficient as weight loss and diarrhea are also prominent symptoms. Choice B is incorrect as it only mentions weight loss, omitting other common manifestations. Choice D is also incorrect as it does not cover the full range of expected clinical signs in Crohn's disease.

Correct Answer: C

Rationale: Hirschsprung disease should be suspected in a newborn with abdominal distention, vomiting, and failure to pass meconium. This condition arises from a congenital absence of nerve cells in a portion of the colon, leading to severe constipation and intestinal obstruction. Pyloric stenosis typically presents with non-bilious projectile vomiting in the first few weeks of life. Intussusception classically manifests with sudden onset of colicky abdominal pain and currant jelly stools. Celiac disease may present with chronic diarrhea, failure to thrive, and abdominal distention but is less likely in this scenario.

Correct Answer: B

Rationale: Melena indicates bleeding from the upper GI tract. The black, tarry appearance of the stool results from the partial digestion of blood as it passes through the intestines, typically originating from sources like the stomach or duodenum. Lower GI bleeding usually presents as bright red blood in the stool, originating from sources like the colon or rectum. Choices A, C, and D are incorrect because melena specifically points to upper GI bleeding rather than issues in the perianal/rectal area, lower GI tract, or hemorrhoids/anal fissures.